H.323 is an International Telecommunications Union (ITU) standard that provides guidelines for terminals and equipment that provide multimedia communications services over computer networks such as packet based networks (PBNs). H.323 terminals and equipment may carry real-time audio, video and/or data.
The packet based network over which H.323 terminals communicate may be a point-to-point connection, a single network segment, or an inter-network having multiple segments with complex topologies, such as local area networks (LANs), Intra-Networks, and Inter-Networks, including the Internet.
H.323 terminals may be used in point-to-point, multi-point, or broadcast (as described in the ITU H.332's standard) configurations. They may interwork with other equipment described in standards, such as H.310 terminals on B-ISDN, H.320 terminals on N—ISDN, H.321 terminals on B-ISDN, H.322 terminals on Guaranteed Quality of Service LANs, H.324 terminals on switched telephone and wireless networks, V.70 terminals on telephone networks, and voice terminals on telephone networks or ISDN through the use of gateways. H.323 terminals may be integrated into personal computers or implemented in stand-alone devices such as video telephones.
Computer networks which are capable of transmitting data or information between locations, such as the above-mentioned Internet, have been used to transmit audio information between computers. At the transmitting computer, a person's voice may be digitized using a conventional analog to digital (A/D) converter and transmitted to the receiving location where it is passed through a conventional digital to analog (D/A) converter and presented as audio. This type of audio connectivity is somewhat similar to flat rate telephony, in that audio information may be transmitted from one location to another by way of a high bandwidth, flat rate communications medium. However, this type of computer telephony system suffers from several major disadvantages. First, the system is limited to only those customers who have access to the Internet and who are using compatible end-point software. In addition, while Internet access has now widely proliferated, it has not reached the near universal accessibility of traditional telephone service over public switched telephone networks (PSTN) and the like. Thus, such a computer telephony system is totally useless if a user on the Internet desires to communicate with someone who does not have access to the Internet.
On the other hand, an H.323-based communications system allows a computer network, such as the Internet, to interact with a conventional telephone network, such as a PSTN, general switched telephone network (GSTN), integrated services digital network (ISDN), or other switched circuit network (SCN), all of which are referred to generally herein as switched circuit networks. Such a system provides the appropriate translation between switched circuit network and packet based network data formats and between different communication procedures, in order to allow a user on one system (such as the PSTN) to communicate with a user on an otherwise incompatible system (such as a packet based network).
While the H.323-based communications system is quite effective at supporting communication between two otherwise incompatible networks, current use of that system has been somewhat limited. The system supports communication between two parties and also provides for conferencing of multiple parties in a single call. However, H.323-based systems do not presently address the provision of more traditional multi-line phone behavior offered in PSTN and other more conventional telecommunications networks. This is a significant drawback, especially for those who are already reluctant to convert from conventional telecommunications networks to an H.323-based system for their telecommunications needs.
Accordingly, it will be apparent to those of ordinary skill in the art that there continues to be a need for a communications system that allows for communication between a packet based network and a conventional switched circuit network, while simultaneously providing various multi-line appearance capabilities offered on switched circuit networks. The present invention addresses these needs and others.